001    /*
002     * Copyright (c) 2007-2014 Concurrent, Inc. All Rights Reserved.
003     *
004     * Project and contact information: http://www.cascading.org/
005     *
006     * This file is part of the Cascading project.
007     *
008     * Licensed under the Apache License, Version 2.0 (the "License");
009     * you may not use this file except in compliance with the License.
010     * You may obtain a copy of the License at
011     *
012     *     http://www.apache.org/licenses/LICENSE-2.0
013     *
014     * Unless required by applicable law or agreed to in writing, software
015     * distributed under the License is distributed on an "AS IS" BASIS,
016     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
017     * See the License for the specific language governing permissions and
018     * limitations under the License.
019     */
020    
021    package cascading.operation.aggregator;
022    
023    import java.beans.ConstructorProperties;
024    
025    import cascading.operation.Aggregator;
026    import cascading.tuple.Fields;
027    import cascading.tuple.Tuple;
028    import cascading.tuple.TupleEntry;
029    
030    /**
031     * Class Last is an {@link Aggregator} that returns the last {@link Tuple} encountered.
032     * <p/>
033     * By default, it returns the last Tuple of {@link Fields#ARGS} found.
034     */
035    public class Last extends ExtentBase
036      {
037      /** Selects and returns the last argument Tuple encountered. */
038      public Last()
039        {
040        super( Fields.ARGS );
041        }
042    
043      /**
044       * Selects and returns the last argument Tuple encountered.
045       *
046       * @param fieldDeclaration of type Fields
047       */
048      @ConstructorProperties({"fieldDeclaration"})
049      public Last( Fields fieldDeclaration )
050        {
051        super( fieldDeclaration.size(), fieldDeclaration );
052        }
053    
054      /**
055       * Selects and returns the last argument Tuple encountered, unless the Tuple
056       * is a member of the set ignoreTuples.
057       *
058       * @param fieldDeclaration of type Fields
059       * @param ignoreTuples     of type Tuple...
060       */
061      @ConstructorProperties({"fieldDeclaration", "ignoreTuples"})
062      public Last( Fields fieldDeclaration, Tuple... ignoreTuples )
063        {
064        super( fieldDeclaration, ignoreTuples );
065        }
066    
067      protected void performOperation( Tuple[] context, TupleEntry entry )
068        {
069        context[ 0 ] = entry.getTupleCopy();
070        }
071      }